A weirdish clock program.

Hey guys, I'm a beginner in java. I'm trying to figure out a way to make a clock, but not one that would call on the computer's clock. Is there a way for java to calculate it by itself?

My end result would be a modified clock, where one second would be .84 of a second. I guess I could merely calculate it out of computer's clock, but if there's a way for my program to calculate time, I'd like it more.